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Abstract

Introduction

Methods

Thirty-two European airlines were asked to provide anonymous data on medical flight
reports of IMEs for the years 2002 to 2007. The total number of incidents was correlated
to revenue passenger kilometers (rpk). Additionally, on-board births and deaths, flight
diversions, flight routes (continental/intercontinental) and involvement of a physician
or medical professional in providing therapy were analysed.

Results

Only four airlines, of which two participated in this study, were able to provide
the necessary data. A total of 10,189 cases of IMEs were analysed. Syncope was the
most common medical condition reported (5307 cases, 53.5%) followed by gastrointestinal
disorders (926 cases, 8.9%) and cardiac conditions (509 cases, 4.9%). The most common
surgical conditions were thrombosis (47 cases, 0.5%) and appendicitis (27 cases, 0.25%).
In 2.8% of all IMEs, an aircraft diversion was performed. In 86% of cases, a physician
or medical professional was involved in providing therapy. A mean (standard deviation)
of 14 (+/- 2.3, 10.8 to 16.6 interquartile range) IMEs per billion rpk was calculated.

Conclusions

The study demonstrates that although aviation is regulated by a variety of national
and international laws, standardised documentation of IMEs is inadequate and needs
further development.

Introduction

As aircraft passenger load increases, presently exceeding 40 million passengers per
year worldwide, in-flight surgical and medical emergencies (IMEs) on commercial aircrafts
also occur quite frequently. A variety of low-cost carriers have made air-travel accessible
to a larger portion of the population, contributing to increasing passenger load.
Additionally, the average passenger age is also steadily rising because of increased
life expectancy in western countries. It has been estimated that by the year 2030,
half of all aircraft passengers will be over 50 years of age [1]. In addition to the continuous increase in the average age of passengers, flight
stress and changes in the cabin environment (temperature, humidity or air pressure),
and other additional factors associated with travel, such as the stress of increased
security, decreased seat space and increasing delays, can also trigger medical emergencies
on board [1].

Although some airlines make an effort to document IMEs as precisely as possible, there
is still a lack of standardisation, resulting in a variety of data, which hampers
epidemiological research on IMEs. This may be a result of the void in legal obligation
for airlines to monitor and report IMEs. However, this epidemiological research is
necessary to adapt and standardise the contents of medical flight kits (MFK) on airplanes,
which have a considerable variability both in medication and equipment [2]. Furthermore, it would be useful to improve preventive strategies in assisting pre-flight
medical screening of patients [3]. Recent data on IMEs is sparse, often based on a single airline and a short time
period, and is not correlated to revenue passenger kilometers (rpk), which does not
allow for an objective analysis [4,5].

In the present study, all documented IMEs of two European airline carriers between
the years 2002 and 2007 were included. The medical flight report statistics provided
by each individual airline were subjected to a descriptive analysis, which included
the frequency and type of emergency. The frequency of aircraft diversion was also
investigated. All data regarding names, ages and the sex of the patient and the name
of the airline were anonymous. The goal of this retrospective study was to document
medically relevant emergencies in airline passengers from 2002 to 2007 on board European
aircraft.

Materials and methods

This study originates from the surgical department of an academic teaching hospital
(Department of General and Visceral Surgery, Augusta Krankenanstalt, Academic Teaching
Hospital of the Ruhr-University Bochum). A total of 32 European airlines were asked
to provide data on IMEs. All patients between January 2002 and December 2007 were
included in the study. The following data were also recorded: on-board births and
deaths, flight diversions, whether the incident occurred on a continental or intercontinental
flight, and the involvement of a physician or medical professional (nurse or paramedic)
in providing therapy.

The authors retrospectively reviewed the available data and classified different categories
of medical and surgical emergencies. Only events that actually happened in the air
after take-off and before landing were included. rpk values were also obtained from
the individual airlines. rpk is a measure of the volume of passengers carried by an
airline; it is the sum of the products obtained by multiplying the number of revenue
passengers carried on each flight by the distance. It describes the total number of
kilometres travelled by all passengers and therefore objectifies data analysis. It
is regularly used in commercial aviation to report the sales volume of passenger traffic.
In order to objectify data, total emergencies per year were related to the airlines'
total rpk.

While handling the data, the regulations of the Ethic commission of the Ruhr-University
Bochum were fully respected (ClinicalTrials.gov Identifier: NCT00713102, Ethical Review
Board of the Ruhr-University Bochum, Germany, registration number: 3207-08). As noted,
evaluation of the data was performed anonymously without any information regarding
the airline or no other passenger details except their illness. Institutional Review
Board approval was obtained and informed consent was waived. The collected data were
compiled in an electronic database (Microsoft Excel for Windows, Microsoft Corp.,
Redmond, WA), mean values for numeric items were calculated and the resulting data
were evaluated.

Results

Of a total of 32 European airlines included in the study, only four were able to provide
the required data with adequate medical flight reports. Two of these did not participate
in the study due to company policy. One airline was able to provide data but did not
qualify for inclusion as the provided diagnoses of the patients were not specific
enough to be included in the study. Twenty-seven airlines were not able to provide
the necessary data for inclusion in the study. After inspection of all available data,
a total of 10,189 patients with an IME on board two European airlines were enrolled
in the study. Data were provided from one airline for the years 2002 to 2007 and from
another for 2006 to 2007. The total rpk analysed in this study included a total of
613.03 billion rpk.

Of all emergencies documented, 20.4% were on continental flights and 79.6% were on
intercontinental flights. A total of 279 diversions occurred among the 10,189 in-flight
patients (2.8%). In the year 2007, 58% of the diversions were on intercontinental
flights and 42% on continental flights. A physician was on board in 77.4% of the diversions.
The most frequent causes for diversion were myocardial infarction (22.7%), apoplexy
(11.3%) and epileptic seizures (9.4%). In 86% of the emergencies between 2002 and
2005, a physician or medical professional (nurse or emergency medical technician)
was involved in on-board patient therapy. Data regarding physician involvement, except
for diversions, were not available for the years 2005 to 2007.

Based on a total of 10,189 emergencies analysed here, an average mean (standard deviation)
of 14 (± 2.3, 10.8 to 16.6 interquartile range) emergencies per billion rpk were calculated.

Aircraft diversion was performed in 279 cases (2.8%) (Table 1). Syncope was by far the most common medical condition reported (5307 cases, 53.5%).
Gastrointestinal disorders were responsible for 8.9% of all emergencies (926 cases).
The third most common medical emergency was cardiac conditions (509 cases, 4.9%),
followed by fear of flying (460 cases, 4.3%) and generalised pain (432 cases, 4.1%).
Details of all diagnoses are summarised in Table 2.

Table 2. Details of medical and surgical in-flight emergencies. Percentages are based on 10,189
incidents from two European airlines January 2002 to December 2007.

Surgical illnesses accounted for a minor percentage of all on-board emergencies. Thrombosis
(47 cases, 0.5%), appendicitis (27 cases, 0.25%) and gastrointestinal bleeding (1
case, < 0.1%) were categorised as surgical emergencies. There were two births (< 0.1%)
and 52 deaths (0.5%) in our study. After analysing the emergencies per rpk, we could
not detect an increase in incidence of IMEs over the years 2002 to 2007. The details
of these findings are summarised in Table 1.

Discussion

Although IMEs are generally rare, they can have a significant effect on other passengers
and crew, potentially with operational implications for the flight [6]. Their incidence has been reported to be one per 10 to 40,000 passengers, with more
than a total of two billion passengers travelling on commercial airlines each year
[7,8]. In order to make the data objective and comparable, we presented it in relation
to rpks. We calculated an average mean of 14 (± 2.3, 10.8 to 16.6) emergencies per
billion rpk for the 10,189 emergencies analysed.

In contrast to recent studies, which suggest that the frequency of IMEs is increasing,
based on our analysis from 2002 to 2007, we were unable to confirm this observation
[9]. However, our analysis should be interpreted with restraint, as not every medical
incident is appropriately documented and, further, this study is not comprehensive,
as only two airlines contributed the analysed data.

Analysing the available data, the breakdown of the various medical emergencies encountered
in our study showed that syncope was by far the most frequent medical condition (5307
cases, 53.5%), followed by gastrointestinal disorders (926 cases, 8.9%) and cardiac
conditions (509 cases, 4.9%), which are similar results to those seen in other studies
[10,11]. One major problem that we encountered was a lack of standardisation in terms of
diagnostic categorisation and confirmed diagnostic data. This was reflected in the
fact that only four out of 32 airlines were able to contribute to the study, only
two of which could ultimately be enroled. Worldwide, it has been reported that only
17% of all IMEs are documented, most of them inconsistently, which would seem to indicate
that legislation for mandatory standardised documentation and the establishment of
an international registry is needed [12].

Flying on commercial aircrafts has been identified as the safest form of travel. Nevertheless,
the special environment in an airplane constitutes a physiological and psychological
stressor for many individuals, potentially triggering a variety of medical emergencies
that may occur on board. This can lead to challenging situations for physicians offering
help. Based on ethical and legal duties, every physician is required to offer help
within his or her scope of practice. The legal duty, however, is only applicable for
certain countries. In the USA, Canada and the UK physicians on airplanes are not required
by law to respond to a call for help [8]. In contrast, the European Union and Australia require physicians on board to do
so.

Physicians helping in IMEs on board airplanes are protected by the so-called Good
Samaritan Act [13]. For airlines registered in the USA, the Medical Assistance Act of 1998 additionally
protects physicians who provide medical help from possible legal consequences. Furthermore,
the Tokyo Convention Act of 1963 allows passengers to take actions which are necessary
to prevent disruptive passengers from endangering the safety of the flight [14]. Other regulations that touch on IMEs differ depending on the origin of the aircraft.
For example, in the USA, the US Federal Aviation Administration (FAA) requires every
US registered commercial aircraft with more than one flight attendant or 12 seats
to carry an automatic external defibrillator (AED). Although most large national European
national airlines carry AEDs, some of them only do so for intercontinental flights.
Unfortunately, there is no law that mandates that an AED must be included in the MFK
for commercial aircrafts registered in Europe.

The MFK contents in European commercial aircrafts are not precisely regulated, which
results in a variety of different medications and equipment on board. In Germany,
the regulations of the National Federal Aviation Agency (Luftfahrt-Bundesamt, Braunschweig,
Germany) and the European Joint Aviation Authorities (JAA; Cologne, Germany) regulate
aviation on the national and continental level. They regulate by law the contents
of an on-board dispensary and the MFK. However, in Europe, the regulations regarding
equipment and medication are loosely formulated, giving airlines broad flexibility
in assembling their MFKs while adhering to the law [15,16]. Now more than ever, cost-cutting pressures on airlines make it unsurprising that
the contents of on-board medical kits differ considerably.

The first author (MS) had the opportunity to compare the MFK of a large national European
national airline with that of a low-cost (no-frills) carrier. Although the national
European airline had excellent equipment, intravenous medications and an AED on board,
the MFK of the low-cost carrier showed only basic equipment without any intravenous
medication or indwelling venous canulas, which could be of importance if reanimation
is needed. Although this is a single experience with one airline, we feel that we
can assume similar discrepancies in comparable airlines. Therefore, it would seem
advisable for some airlines, despite the economic pressure, to reassess their MFKs
with regard to their responsibilities to passengers' safety.

Several studies have shown the use and suitability of expanded mandatory medical kits
introduced on board of US airlines in 1996, which caused the US Federal Aviation Administration
(FAA) to prescribe that an emergency kit with intravenous drugs, AED and other advanced
emergency equipment must be on board [17]. The Air Transport Medicine Committee of the Aerospace Medical Association is continuing
to work on and publish recommendations for MFK contents [18]. Considering the fact that cardiac conditions were the third most common condition
seen in this study (509 cases, 4.9%), patients with cardiac irregularities may profit
from an on-board AED as part of the MFK. The same is true for patients with a suspected
myocardial infarction (34 cases, 0.3%). Apart from passengers who would benefit from
an expanded MFK, flight crew members can also be affected by a medical incident on
board, especially as there are special health risks associated with being an airline
crew member [19,20]. Between 1968 and 1988, Air France reported 10 pilots were incapacitated by cardiac
arrhythmias, seizures and hypoglycaemia during flight [8]. In one incident, carbon dioxide from improperly packed dry ice was the reason for
the incapacitation of an entire cockpit crew [21].

The rate of aircraft diversion in our study was 2.8% (279 diversions). Other studies
report diversion rates of 13% and 7.9%, whereas Cathay Pacific reported 0.35% for
the year 2005 [10,22]. Besides its important medical impact, IMEs leading to aircraft diversion also have
a considerable economic and ecological impact. A fully loaded Boeing 747 needs 23.5
litres kerosene/100 km at the start phase on the ground, which is about 2 km long
and 3.4 litres kerosene/100 km on the climb flight, which is about 100 km. In cases
of flight diversion, the impact of dumping fuel due to weight restrictions for landing
is an additional financial and ecological factor. Besides the logistical challenge,
aircraft diversion is also accompanied by a significant financial loss. The total
costs of a diversion depend on the size of the aircraft, ranging from $30,000 to $725,000
per diversion, which may encourage airlines to focus on improved pre-flight screening
of chronically ill patients [3,10,23].

Conclusions

A standardised epidemiological database documenting IMEs on-board commercial aircrafts
will provide access to potentially valuable data for further flight-epidemiological
research. However, standardisation of IME reporting is necessary for further larger
studies to be conducted, as the current quality of data is poor.

Abbreviations

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

MS participated in the study design, data analysis and interpretation of the data
as well as the writing of the manuscript. FGB participated in the data analysis and
interpretation of the study. DS participated in the data analysis, literature search,
revision of the bibliography, the revision and editing of most of the manuscript.
BM participated in the data analysis, the revision and editing of part of the manuscript.
MS, FGB, DS and BM critically revised the manuscript for intellectual content. All
authors read and approved the final manuscript.